Dual valve fitting for enabling quick measurement of pressure

ABSTRACT

A dual valve fitting enables pressure within a housing to be quickly measured. The fitting defines a passage between its threaded and protuberant ends. The threaded end screws into the housing. In an upper section of the passage, a first valve atop a valve stem features a poppet head that is seatable against an outer valve seat. A first biasing mechanism compels the head against the outer seat to keep the first valve normally closed. In a lower section of the passage, a second valve features a seat piece and a valve retainer. On its periphery, the seat piece carries an o-ring which sealingly secures the piece within the passage. The piece defines an inner bore between its ends and has an inner valve seat on its bottom. The top of the retainer is extendable through this inner bore to a point a dead space apart from a bottom of the stem. Around its bottom, the retainer carries an annular check valve. A second biasing mechanism acts upon the retainer so that the check valve seats against the inner seat thereby rendering the second valve normally closed. When a female coupler of a quick connect device is mated to the protuberant end, it causes the stem to move inwardly so that its head unseats from the outer seat and its bottom moves through the dead space and pushes the retainer to unseat the check valve. This enables air to flow the housing through the fitting into the female coupler.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 08/968,271 filed Nov. 12, 1997.

This application is related to a U.S. application for patent entitledDual Seal Fitting For Enabling Quick Measurement Of Brake CylinderPressure, Ser. No. 08/901,096, filed on Jul. 28, 1997. The copendingapplication is assigned to the assignee of this invention, and itsteachings are incorporated into the present document by reference.

FIELD OF THE INVENTION

The present invention generally relates to a mechanism through which togain access to a pressure to be measured. More particularly, theinvention relates to a dual valve fitting that allows quick measurementof pressure contained within a load sensor of empty and load freightbrake equipment on a railcar.

BACKGROUND OF THE INVENTION

A typical freight train includes one or more locomotives, a plurality ofrailcars and a pneumatic trainline referred to as a brake pipe. Thebrake pipe consists of a series of individual pipe lengthsinterconnected to each other. One pipe length secured to the undersideof each railcar interconnects to another such pipe length via a flexiblecoupler situated between each railcar. The brake pipe supplies thepressurized air that is required by the brake control system to chargethe various reservoirs and operate the air brake equipment on eachrailcar in the freight train.

A train operator situated in the lead locomotive can manipulate a brakehandle to apply and release the brakes on the railcars as desired. Thebrake handle can be moved from and in between a release position at oneextreme in which brake pipe pressure is maximum and the brakes arecompletely released to an emergency position at another extreme in whichbrake pipe pressure is minimal and the brakes are fully applied. Thebrake handle positions thus include brake release, minimum service brakeapplication, full service brake application and emergency brakeapplication. When the brakes are released, the reservoirs and the brakepipe are generally charged to the same pressure: typically 90 psi on afreight train and 110 psi on a passenger train. When the brakes areapplied, the pressure in the brake pipe is reduced via a valve locatedin the lead locomotive. The exact amount by which the pressure isreduced depends into which of the application positions the brake handleis placed. It is this pressure reduction that signals the brake controlvalve on each railcar to supply pressurized air from the appropriatereservoir(s) to the brake cylinders. The brake cylinders convert thispressure to the mechanical force that the brake shoes apply to slow orstop the rotation of the wheels on the railcar.

FIG. 1 illustrates a schematic diagram of the air brake equipment of atypical freight railcar equipped with empty and load brake equipment.The air brake equipment typically includes one or more brake cylinders,an emergency air reservoir, an auxiliary air reservoir and an "ABD" orsimilar type pneumatic brake control valve. The operation of thepneumatic brake control valve as well as a description of its componentsis well known in the railroad industry.

Each freight railcar may include empty and load brake equipment such asa P-1 load proportional valve and an S-1 type or an ELX type load sensorvalve all of which are made by the Westinghouse Air Brake Company(WABCO) and are well known in the brake control art. The objective ofempty and load brake equipment is to reduce braking on the railcar if itis empty and to permit heavier braking on the railcar if it is loaded.On a freight train with railcars equipped with empty and load brakeequipment, the braking is more uniformly applied throughout the train inaccordance with the load borne by the railcars. This tends to reduce theslack between adjacent railcars and improves overall handling of thefreight train.

Regarding the operation of a load sensor valve, the S-1 load sensorvalve, for example, automatically senses whether the railcar is loadedor empty generally by measuring the relationship between the body of therailcar and the top of the side frame of the truck. Each railcartypically has two trucks, one at each end. Each truck includes thewheels and axles and other parts that together form the structure thatsupports the body of the railcar. Suspension springs are used to dampenvibrations that would otherwise be transmitted from the wheels to therailcar body and that may otherwise damage the load being transported.These suspension springs deflect or compress to an extent proportionalto the weight of the load carried by the railcar.

Typically mounted to the underside of the railcar body, the S-1 loadsensor valve uses its sensor arm to measure the distance between therailcar body and the top of the truck side frame. When loaded, therailcar body further compresses the springs thereby reducing thedistance between the railcar body and the truck side frame. The distancethat the sensor arm can travel is therefore limited. Conversely, whenthe railcar is empty, the springs are less compressed thereby maximizingthe distance between the railcar body and the truck side frame. Thedistance that the sensor arm can travel is then at its maximum.

When the S-1 load sensor senses that the railcar is empty, its internalmechanism serves to regulate the flow of air to the P-1 load valve. Whenthe railcar is empty, the P-1 load proportional valve controls the flowof air to the brake cylinder so that the brake cylinder pressure isapproximately 60% of what it would be if the railcar were loaded nomatter how much the pressure is reduced in the brake pipe. During brakeapplications, the equalizing volume is used to maintain a satisfactoryrelationship between pressure in the empty and load brake equipment andthat in the control valve and its reservoirs when the railcar is empty.Empty and load brake equipment such as the type alluded to in thisdocument is described in U.S. Pat. Nos. 5,005,915 and 5,100,207. Thesepatents are assigned to the assignee of the present invention, and theirteachings are incorporated into the present document by reference.

Whether of the S-1 type or ELX type, the load sensor valve features oneor more internal chambers or passageways. An interconnecting pipeconnects at least one of these chambers or passageways to the brakecylinder as shown, for example, in the schematic of FIG. 1. An S-1 loadsensor valve of the type shown schematically in FIG. 1 is illustrated inFIG. 2. The left side of the housing of the load sensor valve features agenerally cylindrical portion flanked by two bolts. Between these boltsand screwed into a threaded bore in the cylindrical portion is a pipeplug. Removal of the pipe plug provides direct access to the chamberthat communicates with the brake cylinder via the interconnected pipeshown in FIG. 1. The threaded bore in the housing can thus be used as anaccess port through which to access the pressure in the brake cylinderfrom the load sensor valve.

The American Association of Railroads (A.A.R.) has proposed that eachrailcar of a freight train be provided with a mechanism that would allowthe pressure within the brake cylinder to be read quickly. At present,the A.A.R. is considering whether to issue a specification requiringthat a commercially available quick connect type fitting be used toaccess the pressure within the brake cylinder. The disadvantage of sucha fitting, however, is that it provides only a single valve with whichto contain the pressure to be measured. That is, while such a fitting isnot being used to access the pressure, it offers only one valve toprevent leakage of the pressure that it supposed to contain. Unless thefitting is routinely covered to protect the valve when the fitting isnot being used to access the brake cylinder pressure, the valve isexposed to dust, dirt and/or other potential contaminants. It is, ofcourse, important that such a fitting prevent leakage of pressure fromthe brake cylinder otherwise operation of the brakes may be adverselyaffected.

It should be noted that the foregoing background information is providedto assist the reader in understanding the instant invention.Accordingly, any terms used herein are not intended to be limited to anyparticular narrow interpretation unless specifically stated otherwise inthis document.

OBJECTIVES OF THE INVENTION

It is, therefore, a primary objective of the invention to provide ahighly reliable fitting that allows the pressure within a brake cylinderof a railcar to be measured quickly.

Another objective is to render the pressure within the brake cylinderquickly measurable with a fitting that features two valves so if onevalve should leak the other valve will prevent leakage of the air thatthe fitting is supposed to contain.

Yet another objective is to design such a dual valve fitting with aprotuberant end with which it can mate with a female coupler of quickconnect device so that the pressure within the brake cylinder can bemeasured quickly by mating the fitting with its corresponding femalecoupler which has attached at its other end a pressure measuring device.

Still another objective of the invention is to provide such a dual valvefitting to enable quick measurement of pressure within any other type ofpiping or vessel capable of holding air or other type of suitable fluidunder pressure.

In addition to the objectives and advantages listed above, various otherobjectives and advantages of the invention will become more readilyapparent to persons skilled in the relevant art from a reading of thedetailed description section of this document. The other objectives andadvantages will become particularly apparent when the detaileddescription is considered along with the attached drawings and with theappended claims.

SUMMARY OF THE INVENTION

In a presently preferred embodiment, the invention provides a dual valvefitting for enabling quick measurement of pressure contained within ahousing. The dual valve fitting includes a single valve body thatdefines a flow passage from its threaded end to its protuberant end. Theprotuberant end is shaped to mate with a female coupler of a quickconnect device. The threaded end is designed to screw into a threadedbore of the housing. Situated in an upper section of the flow passage, afirst valve features a poppet head at a top end of a valve stem. Thepoppet head is seatable against an outer annular valve seat formed inthe protuberant end of the flow passage. A first mechanism for biasingcompels the poppet head against the outer annular valve seat so that thefirst valve is normally closed. Situated in a lower section of the flowpassage, a second valve features a seat piece and a valve retainer. Onits outer periphery, the seat piece carries an o-ring by which the seatpiece sealingly secures within the flow passage adjacent to the firstmechanism for biasing. Formed on its bottom end, the seat piece has aninner annular valve seat. Between its ends, the seat piece defines aninner bore. The top end of the valve retainer is extendable through thisinner bore to a point a dead space apart from a bottom end of the valvestem. Around its bottom end, the valve retainer carries an annular checktype valve that is seatable against the inner annular valve seat. Asecond mechanism for biasing acts upon the valve retainer so that itscheck type valve seats against the inner annular valve seat therebyrendering the second valve normally closed. When such female coupler ismated with the protuberant end, the valve stem moves inwardly with itspoppet type head unseating from the outer annular valve seat and itsbottom end moving through the dead space and pushing against the top endof the valve retainer to unseat the check type valve. This enables flowfrom such housing through the flow passage into such female coupler.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of air brake equipment for a typicalfreight railcar including an S-1 load sensor valve.

FIG. 2 is a side view of the S-1 load sensor valve shown schematicallyin FIG. 1.

FIG. 3a is a front view of a dual valve fitting according to a firstembodiment of the invention, a rear view thereof being the same as thefront view.

FIG. 3b is a cross sectional view of the dual valve fitting shown inFIG. 3a.

FIG. 3c-d are partial cut away views of the dual valve fitting shown inFIG. 3a.

FIG. 3e is a bottom view of the dual valve fitting shown in FIG. 3a.

FIG. 3f is a perspective, exploded view of the dual valve fitting shownin FIG. 3a.

FIG. 3g is a cross sectional view of a protective cap that may be usedto protect the invention from contaminants.

FIG. 3h is a cross sectional view of the dual valve fitting showinghoused therein a shaft protruding from the bottom end of a valveretainer.

FIG. 4 is a cross sectional view of a dual valve fitting according to asecond embodiment of the invention.

FIG. 5 is a cross sectional view of a dual valve fitting according to athird embodiment of the invention.

FIG. 6 is a cross sectional view of a dual valve fitting according to afourth embodiment of the invention.

FIG. 7 is a cross sectional view of a dual valve fitting according to afifth embodiment of the invention.

FIG. 8 is a cross sectional view of a dual valve fitting according to asixth embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Before describing the invention in detail, the reader is advised that,for the sake of clarity and understanding, identical components havingidentical functions in each of the accompanying drawings have beenmarked where possible with the same reference numerals in each of theFigures provided in this document.

FIGS. 1 and 2 each illustrate a housing 701 of an S-1 load sensor valve700. The housing 701 defines a chamber or internal passageway 702 thatcommunicates with a brake cylinder 800 of a railcar. Typically, aninterconnecting pipe 801 connects the chamber 702 to the brake cylinder800. The housing 701 also defines a threaded bore/pipe tap 703 thatcommunicates with the chamber 702, as best shown in FIG. 2. Removing apipe plug 704 from the pipe tap 703 provides direct access to chamber702. Pipe tap 703 can thus be used as an access port through which toaccess the pressure in the brake cylinder from the S-1 load sensorvalve.

FIGS. 3a-h and 4-6 illustrate the essential details of the variousembodiments of the present invention, namely, a dual valve fitting. Thedual valve fitting in each of these embodiments enables quickmeasurement of the brake cylinder pressure within the housing of an S-1type or an ELX type load sensor valve or load sensor valves made byvarious other railroad equipment manufacturers. It should be apparentfrom a reading of this document that the dual valve fitting describedand claimed herein can, of course, be applied to any other type ofhousing, piping or vessel capable of holding air or other fluid underpressure.

In a first embodiment shown in FIGS. 3a-f, the dual valve fitting 1basically includes a valve body 2, a valve retainer 3, first and secondsealing rings 4 and 5 and a means for biasing 6 the valve retainer 3within a flow passage 7 defined by the valve body 2. The valve body 2has a protuberant end 20 that is shaped to mate with a female coupler ofa quick connect device. The valve body 2 also has a threaded end 21 thatis designed to screw into the threaded bore 703 of any suitable housingsuch that of the S-1 load sensor valve 700.

The valve retainer 3 defines around itself first and second annularrecesses 31 and 32. These annular recesses 31 and 32 are spaced apartfrom each other so as to match the spacing of outer and inner annularvalve seats 71 and 72 formed in the flow passage 7. Forming a firstvalve, the first sealing ring 4 fits into the first annular recess 31 soas to seat against the outer annular valve seat 71 when the first valveis closed. Forming a second valve, the second sealing ring 5 lodges intothe second annular recess 32 so as to seat against the inner annularvalve seat 72 when the second valve is closed. The sealing rings 4 and 5may be composed of rubber or any other suitable sealing material.

The means for biasing 6 acts upon the valve retainer 3 so that the firstand second sealing rings 4 and 5 seat against the outer and innerannular valve seats 71 and 72, respectively. The means for biasing 6thus renders the first and second valves normally closed. It is in thisnormally closed position which these valves are shown in FIG. 3b. FIGS.3c-d show the first and second valves in the open position.

The valve retainer 3 is designed so that the first annular recess 31 hasa diameter smaller than the second annular recess 32. The first andsecond sealing rings 4 and 5, of course, must have their internaldiameters dimensioned accordingly so that each sealing ring properlyretains within its respective recess. Similarly, the flow passage 7 isshaped so that the outer annular valve seat 71 has an internal diameterthat is smaller than that of the inner annular valve seat 72. It is thisarrangement that provides the first valve with a smaller effectivediameter than that of the second valve. The first and second valves thusreside in their normally closed positions by virtue of the action of themeans for biasing 6 on valve retainer 3. When in the closed position,the first and second valves thus each prevent leakage of the airpressure from the housing 701.

The means for biasing 6 preferably includes a retaining ring 60 and aspring 62, as best shown in FIG. 3f, though it can take the form ofvarious other types of mechanical apparatus. The retaining ring 60securely wedges into an annular groove 25 that is formed in the flowpassage 7 near the bottommost part of threaded end 21 of valve body 2.The spring 62 is disposed between the retaining ring 60 and a bottom endof valve retainer 3. The spring 62 thus compresses the first and secondsealing rings 4 and 5 into the outer and inner annular valve seats 71and 72. The retaining ring 60 may also include a washer 61 to furthersupport the bottom of spring 62 within the flow passage 7 of valve body2.

The valve body 2 also includes a hexagonal outer portion 24 between theprotuberant and threaded ends 20 and 21 to accommodate a wrench withwhich to screw securely the fitting 1 into the threaded bore 703 of thehousing 701. Disposed within a groove formed adjacent to an underside ofthe hexagonal outer portion 24 adjacent the threaded end 21 of valvebody 2 is an o-ring. When the threaded end 21 of the dual valve fittingis screwed into the threaded bore 703, it is with this o-ring that thevalve body 2 is sealed against the housing. Alternatively, this seal maybe implemented using a pipe tap arrangement.

Mating such a female coupler of such quick connect device to theprotuberant end 20 of the dual valve fitting 1 causes the valve retainer3 to move inwardly against the spring 62. This moves the first andsecond valves away from the outer and inner valve seats 71 and 72. Withboth the first and second valves open, air is allowed to flow from thehousing into the threaded end 21 of flow passage 7. The air continuesflowing past spring 62 around valve retainer 3 until it emerges from theprotuberant end 20 of flow passage 7. Finally, the air stream passesinto the female coupler. Using a pressure measuring device connected tothe opposite end of the female coupler, the pressure of the aircontained within the housing can thus be quickly read.

Referring to FIG. 3f, the valve retainer 3 may also feature a shaft 33,cylindrical or otherwise, about which spring 62 can be disposedconcentrically to further stabilize the biasing means 6. As shown inFIG. 3h, this shaft 33 may be made long enough so as to protrude fromthe threaded end 21 when the dual valve fitting 1 is coupled with afemale coupler. When used to access pressure in certain housing whichhave yet a third valve located at the bottom of the threaded bore, thedual valve fitting via shaft 33 can be used to unseat this third valve.

It is also preferred that the outer and inner valve seats 71 and 72 beformed within flow passage 7 so that the first valve opens before, andcloses after, the second valve. With this closing sequence, the dualvalve fitting 1 protects against leakage should dust, dirt or othercontaminants prevent the outer, first valve from closing completely. Asbest shown in FIG. 3c, it is also preferred that the top end of valveretainer 3 never leave the top section 17 of flow passage 7 when boththe first and second valves are completely opened.

In a second embodiment shown in FIG. 4, the dual valve fitting 100includes first and second valve bodies 101 and 201. The first valve body101 has a protuberant end 120 that is shaped to mate with a femalecoupler of a quick connect device. The first valve body 102 also has athreaded end 121 that is designed to screw into the second valve body201 as provided below. Defined within the first valve body between itsends is a flow passage 107. An outer annular valve seat 112 is formedwithin flow passage 107 at or near the opening of protuberant end 120.

Situated in flow passage 107, a first valve features a poppet type head115 at a top end of a valve stem 110. The poppet type head 115 may becomposed of rubber or any other suitable sealing material. A first meansfor biasing 130 compels the poppet type head 115 against the outerannular valve seat 112. The first means for biasing preferably includesa first retaining ring 131 and a first spring 132, though it can takethe form of various other types of mechanical apparatus. The retainingring 131 is secured within an annular groove 108 formed within flowpassage 107 of first valve body 101. The first spring 132 is disposedconcentrically about valve stem 110 between the first retaining ring 131and the underside of poppet type head 115. It is first spring 132 thatforces the poppet type head 115 against the outer valve seat 112 so thatthe first valve is normally kept closed.

The second valve body 201 has an upper, internally threaded end 220 thatis designed to accommodate the threaded end 121 of first valve body 101.The second valve body also has a lower threaded end 221 that isscrewable into the threaded bore 703 of any suitable housing such asthat of the S-1 load sensor valve 700. Defined within the second valvebody between its ends is a flow bore 207 that communicates with the flowpassage 107 of first valve body 101.

Situated in flow bore 207, a second valve features a retainer 209 thatdefines in its top end a recess 252. Retained i n this recess is a checktype valve 253 whose top side is seatable against an inner annular valveseat 245 formed in flow bore 207. The check type valve may be composedof rubber or any other suitable sealing material. A second means forbiasing 230 acts upon retainer 209 so that the check type valve 253therein seats against the inner annular valve seat 245. The second meansfor biasing 230 preferably includes a second retraining ring 231 and asecond spring 232, though it can take the form of various other types ofmechanical apparatus. The second retaining ring is retained within anannular groove 208 formed within flow bore 207 at the lower threaded end221 of second valve body 201. The second spring 232 is disposed betweenthe second retaining ring 231 and the bottom end of the retainer 209.The bottom end of retainer 209 may feature a shaft, cylindrical orotherwise, about which second spring 232 can be disposed concentricallyto further stabilize the second biasing means 230. It is second spring232 that forces the check type valve 253 in retainer 209 against theinner annular valve seat 245 so that the second valve is normally keptclosed.

The dual valve fitting 100 also includes a stem extension 264 disposedbetween a bottom end of valve stem 110 and the top side of check typevalve 253. The stem extension at its top preferably defines a cavityinto which the bottom end of valve stem 110 protrudes even when thefirst valve is closed. Preferably a dead space 266 is provided betweenthe bottom end of valve stem 110 and the top of stem extension 264within this cavity. By virtue of dead space 266, the poppet type head115 can be unseated from the outer annular valve seat 112 while thecheck type valve 253 remains seated on inner annular valve seat 245.With the first valve opened in this manner, the integrity of the secondvalve can thus be tested when the dual valve fitting 100 is connected toa pressure bearing housing such as the S-1 load sensor valve 700.

The first valve body 101 may also include a hexagonal outer portion 124between the protuberant and threaded ends 120 and 121 to accommodate awrench with which to screw first valve body 101 into the upper threadedend 220 of second valve body 201. Disposed within a groove formedadjacent to an underside of the hexagonal outer portion 124 adjacent thethreaded end 121 is an o-ring. When the threaded end 121 of first valvebody 101 is screwed into the upper threaded end 220, it is with thiso-ring that the first valve body 101 is sealed against second valve body201. This seal may instead be implemented using a pipe tap arrangement.

The second valve body 201 also defines an annular groove formed on itsoutside surface above its lower threaded end 221. An o-ring 228 securelyfits into this groove. It is with this o-ring 228 that the second valvebody 201 is sealed against the housing 701 when the lower threaded end221 is screwed into the threaded bore 703 of the housing. This seal,too, may be implemented using a pipe tap arrangement.

Mating the female coupler of the quick connect device to the protuberantend 120 of the dual valve fitting 100 causes the valve stem 110 to moveinwardly against first spring 132. Through such movement, the bottom endof valve stem 110 moves through and beyond dead space 266 and into thetop of stem extension 264. The bottom of stem extension 264, in turn,drive check type valve 253 off inner annular valve seat 245 as retainer209 moves inwardly against second spring 232. With both the first andsecond valves open, air is allowed to flow from the housing into thelower threaded end 221 of flow bore 207. The flow of air continues pastsecond spring 232 around retainer 209 and stem extension 264 into flowpassage 107 of first valve body 101. Flowing past first retaining ring131, first spring 132 and poppet type head 115, the air emerges from theprotuberant end 120 of flow passage 107. Finally, the air stream passesinto the female coupler. Using a pressure measuring device connected tothe opposite end of the female coupler, the pressure of the aircontained within the housing can thus be quickly read.

In a third and a fourth embodiment shown in FIGS. 5 and 6, respectively,the dual valve fitting also includes first and second valve bodies. Thefirst valve body along with the first valve and the first means biasingthat it accommodates are generally identical to that of the secondembodiment.

The second valve body has an upper, internally threaded end 320 that isdesigned to accommodate the threaded end 121 of first valve body 101.The second valve body also has a lower threaded end 321 that isscrewable into the threaded bore 703 of any suitable housing such asthat of the S-1 load sensor valve 700. Defined within the second valvebody between its ends is a flow bore 307 that communicates with flowpassage 107 of the first valve body 101.

Situated in flow bore 307, a second valve features a plunger whose topend is disposed opposite the bottom end of valve stem 110. The bottomend of the plunger defines an annular groove in which is retained ameans for sealing. This means for sealing is designed to seat against aninner annular valve seat formed in flow bore 307. The means for sealingmay be composed of rubber or any other suitable sealing material. Asecond means for biasing acts upon the plunger so that the means forsealing seats against the inner annular valve seat.

In the third embodiment of the invention shown in FIG. 5, disposed inflow bore 307 approximate its lower threaded end 321 is an annularflange 310 on whose underside is formed the inner annular valve seat311. The means for sealing 330 that is seatable against this inner valveseat 311 is an o-ring 331. Formed on a top side of annular flange 310 isa lower annular spring seat 312. Formed on plunger 309 near its top endis an upper annular spring seat 313. Spring seat 313 may also becomprised of annular groove defined within plunger 309 in which toretain an retaining ring to serve as the spring seat 313. Along withlower and upper springs seats 312 and 313, the second means for biasing340 includes a second spring 342 disposed concentrically about plunger309 between the spring seats. Spring 342 compresses o-ring 331 againstthe inner annular valve seat 311 so as to keep the second valve normallyclosed. The second means for biasing 340 can also take the form ofvarious other types of mechanical apparatus.

In the fourth embodiment of the invention illustrated in FIG. 6, themeans for sealing 345 preferably takes the form of an annular check typevalve 346 that is molded to an annular groove 347 disposed about thebottom end of plunger 319. The second means for biasing 350 preferablyincludes a second retaining ring 351 is retained within an annulargroove 353 formed in the lower threaded end 321 of flow bore 307. Secondspring 352 is disposed between this second retaining ring and the bottomend of plunger 319. Spring 352 compresses check valve 346 against theinner annular valve seat 361 so as to keep the second valve normallyclosed.

Referring to both the third and fourth embodiments of the invention, adead space 366 is preferably provided between the bottom end of valvestem 110 and the top end of the plunger. By virtue of dead space 366,the poppet type head 115 can be unseated form the outer annular valveseat 112 while the second valve remains closed. With the first valveopened in this manner, the integrity of the second valve can thus betested when the dual valve fitting is connected to a pressure bearinghousing such as the S-1 load sensor valve 700.

As with the second embodiment, the second valve body of both the thirdand fourth embodiments may also define an annular groove formed on itsoutside surface above its lower threaded end. An o-ring 228 securelyfits into this groove. It is with this o-ring/annular groove arrangementor a pipe tap arrangement that the second valve body can seal againstthe housing 701 when its lower threaded end 321 is screwed into thethreaded bore 703 of the pressure bearing housing.

Regarding the operation of the third and fourth embodiments of the dualvalve fitting, mating the female coupler of the quick connect device tothe protuberant end 120 of first valve body 101 causes the valve stem110 to move inwardly against first spring 132. Through such movement,the bottom end of valve stem 110 moves through and beyond dead space 366and into the top of the plunger. The bottom of the plunger, in turn,drives the means for sealing off the inner annular valve seat as theplunger moves inwardly against the second spring. With both the firstand second valves open, air is allowed to flow from the housing into thelower threaded end 321 of flow bore 307. The flow of air continues pastthe second spring around the plunger into flow passage 107 of firstvalve body 101. Flowing past first retaining ring 131, first spring 132and poppet type head 115, the air emerges from the protuberant end 120of flow passage 107. Finally, the air stream passes into the femalecoupler. Using a pressure measuring device connected to the opposite endof the female coupler, the pressure of the air contained within thehousing can thus be quickly read.

In an aspect related to the third and fourth embodiments, the inventionalso provides an auxiliary valve assembly. The auxiliary valve assemblypreferably takes the form of the second valve body of the third andfourth embodiments and is intended to be implemented in conjunction witha male plug of a quick connect device. There are, of course, a varietyof quick connect devices commercially available in the market place. Themale plug of a standard, commercially available quick connect devicewould need only be modified to work with the auxiliary valve assembly tomake the dual valve fitting in its third and fourth embodiments. Forexample, the male plug of a standard coupling would have to be modifiedto mate and interact with the secondary valve body and its associatedcomponents such as its upper threaded end and plunger.

In a fifth embodiment shown in FIG. 7, the dual valve fitting has onlyone valve body 401. The valve body 401 has the protuberant end 120 andthe threaded end 121 between which is defined a flow passage 407. Thethreaded end 121 is screwable into the threaded bore 703 of any suitablehousing such as that of the S-1 load sensor valve 700. Outer annularvalve seat 112 is formed within flow passage 407.

Situated in the upper section of flow passage 407, the first valvefeatures the poppet type head 115 on the top end of valve stem 110. Thefirst means for biasing 130 compels the poppet head 115 against theouter valve seat 112. Though it can take the form of various other typesof mechanical apparatus, the first means for biasing preferably includesthe first spring 132 and an annular flange 410 on whose top side isformed an upper spring seat 431. The first spring 132 is disposedconcentrically about valve stem 110 between seat 431 and the undersideof poppet head 115. First spring 132 forces the poppet head 115 againstthe outer valve seat 112 so that the first valve is normally keptclosed.

Situated in the lower section of flow passage 407, a second valvefeatures a retainer 409 that defines in its top end a recess 452.Retained in this recess is a check type valve 453 whose top side isseatable against an inner annular valve seat 445 formed on the bottomside of annular flange 410. Though it can be implemented in other ways,the second means for biasing 230 preferably includes a retaining ring231 and a second spring 232. The second retaining ring is retainedwithin an annular groove 208 formed within flow passage 407 at thethreaded end 121 of valve body 401. Second spring 232 is disposedbetween retaining ring 231 and the bottom end of retainer 409. It issecond spring 232 that pushes check valve 453 in retainer 409 againstthe inner annular valve seat 445 so that the second valve is normallykept closed.

In this fifth embodiment, the dead space 266 is preferably providedbetween the bottom end of valve stem 110 and the top side of check valve453. The dead space 266 allows poppet head 115 to be unseated from outervalve seat 112 while check valve 453 remains seated on inner valve seat445. With the first valve opened in this manner, the integrity of thesecond valve can thus be conveniently and quickly tested.

The valve body 401 also preferably includes the hexagonal outer portion124 between its protuberant and threaded ends to accommodate a wrenchwith which to screw valve body 401 into a suitable housing. Disposedwithin a groove formed adjacent to an underside of the hexagonal outerportion is o-ring 419. It is with this o-ring 419 or a pipe taparrangement that valve body 401 seals against such a housing whenthreaded end 121 is screwed into the threaded bore 703 of such apressure bearing housing.

The retainer 409, as part of its bottom end, may also feature a shaft433, cylindrical or otherwise, about which spring 232 can be disposedconcentrically to further stabilize the biasing means 230. As shown inFIG. 7, this shaft 433 may be made long enough so as to protrude fromthe threaded end 121 when the dual valve fitting is coupled with afemale coupler. When used to access pressure in certain housings whichhave yet a third valve located at the bottom of the threaded bore, thedual valve fitting via shaft 433 can be used to unseat this third valve.

In a presently preferred sixth embodiment shown in FIG. 8, the dualvalve fitting also has only one valve body 501. The valve body 501 hasthe protuberant end 120 and the threaded end 121 between which isdefined a flow passage 507. The threaded end 121 is screwable into thethreaded bore 703 of any suitable housing such as that of the S-1 loadsensor valve 700. Outer annular valve seat 112 is formed within flowpassage 507.

Situated in the upper section of flow passage 507, the first valvefeatures the poppet type head 115 on the top end of valve stem 110. Thefirst means for biasing 130 compels the poppet head 115 against theouter valve seat 112. Though it can be implemented using other types ofapparatus, the first means for biasing preferably includes a spring stop131 and a first spring 132. The spring stop 131 may be held in place viaa projecting rim that can secure within an annular groove defined inflow passage 507. First spring 132 is disposed concentrically aboutvalve stem 110 between stop 131 and the underside of poppet head 115.First spring 132 thus biases the first valve in the closed position.

A cylindrical seat piece 540 features an annular groove around itscircumference in which it retains an o-ring 542. It is with this o-ring542 that seat piece 540 is sealingly secured within flow passage 507.The bottom end 545 of seat piece 540 is shaped as an inner annular valveseat and its opposite end 546 is situated adjacent to the spring stop131. Along its longitudinal axis, the seat piece 540 also definesthrough itself an inner bore 548. Extending through this inner bore 548from the upper to the lower section of flow passage 507 is a valveretainer 550.

Situated in the lower section of flow passage 507, a second valveincludes valve retainer 550 and the inner annular valve seat 545 of seatpiece 540. The top end of valve retainer 550 is extendable through theinner bore 548 of seat piece 540 to a point preferably a dead space 266apart from the bottom end of valve stem 110. Around its bottom end,valve retainer 550 carries an annular check type valve 553.

In this sixth embodiment of the invention, the second means for biasing230 acts upon valve retainer 550 so that the check type valve 553therein seats against the inner annular valve seat 545. Though it can beimplemented in alternative ways, the second means for biasing 230preferably includes essentially the same structure as that described forthe fifth embodiment of the invention. Consequently, it is second spring232 that forces check type valve 553 of retainer 550 against the innerannular valve seat 545 so that the second valve is normally kept closed.The dead space 266, of course, will allow the first valve to be openedso that the integrity of the second valve can be quickly tested.

The dual valve fitting of this sixth embodiment likewise preferablyincludes other previously described features. This includes featuressuch as hexagonal portion 124 along which either the o-ring/groovearrangement or the pipe tap arrangement with which valve body 501 sealsagainst the pressure bearing housing. The dual valve fitting may alsofeature a shaft 533 formed as part of the bottom end of valve retainer550. Shaft 533 is preferably made long enough so as to protrude from thethreaded end 121 when the dual valve fitting is coupled with a femalecoupler. When used to access pressure in certain housings which have yeta third valve located at the bottom of the threaded bore, shaft 533allows the dual valve fitting to unseat this third valve.

Referring to all embodiments of the invention, the position of the firstvalve renders it most exposed to dust, dirt and other potentialcontaminants. The second valve thus serves as a backup to the firstvalve should the first valve succumb to such contaminants or otherwisedegrade. Conversely, should the second valve degrade, the first valveacts as the backup valve to prevent leakage of air or other fluid fromwhatever pressure bearing housing to which the invention is connected.

A protective cap may be used to cover the protuberant end of theinvention to protect it from contaminants when it is not being used. Asshown in FIG. 3g in the context of the first embodiment, thoughapplicable to all other embodiments, the protective cap 8 features acover 81, a washer 82 and a strap 83. The strap 83 is used to connectthe cover 81 to the washer 82 to reduce the likelihood of losing ormisplacing the protective cap 8. The washer 82 has an inner diameterthat allows it to clip securely into a corresponding annular recess 23borne by valve body 2, as shown in FIG. 3a, to hold the protective cap 8onto the dual valve fitting. The cover 81 is dimensioned so that it cansnugly grip the protuberant end 20, yet still easily clip on and off ofthe dual valve fitting. The dual valve fitting described and claimed inthis document can, of course, be applied to many types of housings,pipes or vessels capable of holding air or other type of suitable fluidunder pressure.

The presently preferred and alternative embodiments and related aspectsfor carrying out the invention have been set forth in detail accordingto the Patent Act. Those persons of ordinary skill in the art to whichthis invention pertains may nevertheless recognize various alternativeways of practicing the invention without departing from the spirit andscope of the appended claims. Those of such skill will also recognizethat the foregoing description is merely illustrative and not intendedto limit any of the ensuing claims to any particular narrowinterpretation.

Accordingly, to promote the progress of science and useful arts, wesecure for ourselves by Letters Patent exclusive rights to all subjectmatter embraced by the following claims for the time prescribed by thePatent Act.

We claim:
 1. A dual valve fitting for enabling quick measurement ofpressure contained within a housing, said fitting comprising:(a) a valvebody defining a flow passage therethrough from a protuberant end of saidvalve body to a threaded end of said valve body, said protuberant endbeing shaped to mate with a female coupler of a quick connect device,said threaded end for screwing into a threaded bore of such housing; (b)a first valve situated in an upper section of said flow passage, saidfirst valve including a poppet type head at a top end of a valve stemfor seating against an outer annular valve seat formed within said flowpassage at said protuberant end thereof; (c) a first means for biasingsaid poppet type head against said outer annular valve seat so that saidfirst valve is normally closed; (d) a second valve situated in a lowersection of said flow passage, said second valve including (A) a seatpiece having (i) an outer periphery that carries an o-ring by which saidseat piece sealingly secures within said flow passage adjacent to saidfirst means for biasing, (ii) an inner bore defined therethrough and(iii) an inner annular valve seat formed at a bottom end thereof and (B)a valve retainer having (i) a top extendable through said inner bore toa point a dead space apart from a bottom end of said valve stem and (ii)a bottom end carrying thereabout an annular check type valve that isseatable against said inner annular valve seat; and (e) a second meansfor biasing said valve retainer so that said check type valve seatsagainst said inner annular valve seat thereby rendering said secondvalve normally closed; such that mating such female coupler with saidprotuberant end causes inward movement of said valve stem with saidpoppet type head thereof unseating from said outer annular valve seatand said bottom end thereof moving through said dead space and pushingagainst said top end of said valve retainer to unseat said check typevalve thereby enabling flow from such housing through said flow passageinto such female coupler.
 2. The dual valve fitting recited in claim 1wherein said first means for biasing includes:(a) a spring stop securedwithin an annular groove formed within said upper section of said flowpassage; and (b) a first spring disposed between said spring stop and anunderside of said poppet type head to compress said poppet type headagainst said outer annular valve seat.
 3. The dual valve fitting recitedin claim 1 wherein said second means for biasing includes:(a) aretaining ring retained within an annular groove formed in said flowpassage at said threaded end of said valve body; and (b) a second springdisposed between said retaining ring and said bottom end of said valveretainer to compress said check type valve against said inner annularvalve seat.
 4. The dual valve fitting recited in claim 1 wherein a shaftformed as part of said bottom end of said valve retainer isconcentrically situated within said second means for biasing andprotrudes from said threaded end when such female coupler is mated tosaid dual valve fitting.